The MAX5943 is a fully integrated power-management IC for FireWire applications. This device controls two external power n-channel MOSFETs to regulate current from the input power supply to the load and performs low-voltage-drop, power-supply ORing. The MAX5943 operates over a 7.5V to 37V input range and provides inrush and output current limit in addition to a diode ORing function suitable for FireWire applications. The MAX5943 allows the safe insertion and removal of FireWire peripherals into a live FireWire port by providing inrush current control and an output current-limiting function. The ORing feature provides a very efficient way to protect the FireWire port when connected to another FireWire peripheral that sources a higher voltage. By turning off both external MOSFETs, the MAX5943 provides a true bidirectional load disconnect. A low-current shutdown mode disables the MAX5943, resulting in less than 10µA supply current. A pin-selectable input allows latched or autoretry fault management after a fault. The MAX5943A features a current-limit function that actively limits the current drawn by the load with a programmable timeout. The MAX5943B–MAX5943E do not actively limit the load current but provide a circuit-breaker function. See the Selector Guide for the default and programmable circuit-breaker timeouts. The MAX5943 operates over the -40°C to +85°C extended temperature range and is available in a 16-pin QSOP package.
The MAX5943 is a fully integrated power‑management IC designed for FireWire applications. It controls two external N‑channel MOSFETs to regulate current, provide inrush control, and perform low‑drop power‑supply ORing, enabling safe hot‑swap of FireWire peripherals.
Key features include an input voltage range of 7.5 V to 37 V, shutdown current as low as 5‑10 µA, programmable active current‑limit (MAX5943A) or circuit‑breaker (MAX5943B‑E), and operation over a –40 °C to +85 °C temperature range in a 16‑pin QSOP package.
| Supply Voltage Range (VIN) | 7.5 V – 37 V |
|---|---|
| Supply Current (no load) | 1.3 mA – 23 mA |
| Shutdown Current | 5 µA – 10 µA |
| Undervoltage Lockout (VUVLO) | 6.2 V – 6.8 V |
| Operating Temperature Range | -40 °C to +85 °C |
| Package | 16‑pin QSOP |
The MAX5943 operates from 7.5 V up to 37 V.
The MAX5943A variant includes an active current‑limit function; the MAX5943B‑E variants provide a circuit‑breaker function instead.
The shutdown current is specified as 5 µA to 10 µA.
The device is supplied in a 16‑pin QSOP package.